Generally mixtures of transparent miscible polymers provide stable blends possessing optical clarity and a useful balance of mechanical properties depending upon properties of the individual blend components. By contrast, when two transparent immiscible polymers are blended, the mixture is generally hazy and exhibits light transmission properties which are less desirable than those of the individual components unless the refractive indices of the two transparent immiscible polymers are very nearly equal, i.e., differ by less than about 0.005.
There is a long standing need for ways of blending immiscible polymers with dissimilar refractive indices to obtain polymer blends with good optical properties, including low haze. Attempts to satisfy the need for transparent blends have concentrated on the selection or development of a second polymer with a refractive index to match the refractive index of the first polymer in the blend. This method has been quite restrictive to the development of transparent polymer blends.